The proposed studies are directed at the hypothesis that immunological events underlie the pathogenesis of rheumatic syndromes, such as rheumatoid arthritis and systemic lupus erythematosus and further that these immunological changes of the host may result from atypical microbial infection. Efforts to characterize the gamma globulin complexes in biological fluids will continue -- seeking identity of the immune reactants involved. Direct and indirect efforts to identify and characterize microbial agents in tissue from rheumatic disease patients will continue. Techniques that have been successful in the demonstration of latent infection in other models of disease will be employed. Emphasis will be placed on the study of immunoglobulins and lymphocytes which derive from tissue culture preparations of rheumatoid synovia. Based on the observations that there is continued replication of lymphocytes in culture and concomitant maintenance of immunoglobulin synthesis over many weeks, there will be an effort to determine the immunological specificity of both humoral and cellular immunity.